1. Field of the Invention
The present invention relates generally to printing presses and more particularly to reducing noise associated with printing sleeves of printing presses.
2. Background Information
Printing forms in tubular shape, also known as printing sleeves, have been used in a variety of printing applications. For example, printing sleeves used as printing blankets for offset printing are known, as are printing sleeves for flexographic printing. These sleeves typically are slid axially over a respective cylinder with the aid of compressed air exiting from holes in the outer surface of the cylinder. The compressed air helps to expand the sleeve to ease the placement or removal of the sleeve over the cylinder. However, the compressed air also can create a whistle or noise, which may be desirable to reduce.
It is desirable to have a taper at the end of the cylinder to help start the installation of the printing sleeve over the cylinder. This taper has been found to increase the whistle or noise. Removal of the taper can help reduce the noise but makes sleeve installation more difficult.
U.S. Pat. No. 5,215,213 discloses a tubular printing blanket with a damping ring for placement on the inside of a blanket. The damping ring purportedly damps vibrations of the sleeve caused by pressurized flow of air and reduces the resultant noise. The printing blanket fits axially over a blanket cylinder with a continuous outer surface having air holes and a tapered edge surface.
The device of the ""213 patent has several disadvantages, including: (1) that a damping ring is required to be placed on every sleeve, so that the costs of each sleeve are increased; and (2) that the damping ring has been found to not reduce noise levels for every axial location of the sleeve as the sleeve is slid over a respective cylinder, i.e. that the escaping air still creates noise as the sleeve is being slid on, and only adequately reduces noise when the blanket is placed fully over the cylinder. Thus noise still results during an axial sliding operation even with the damping rings.
An object of the present invention is to reduce noise associated with the axial removal and placement of printing sleeves.
A preferred embodiment of the present invention provides a printing press comprising a cylinder having an outer surface and a plurality of air holes for providing air to the outer surface, a sound-damping material located on a section of the outer surface, and an axially-removable printing sleeve for fitting over the outer surface of the cylinder.
Advantageously, by having the sound deadening material on the outer surface of the cylinder, the sleeve itself need not have any damping material. Moreover, noise may be reduced even as the sleeve is being removed.
Preferably, the sound dampening material contacts the printing sleeve during the axial removal of the printing sleeve.
The printing press may be an offset lithographic printing press and the printing sleeve a blanket.
The sound-damping material preferably is made of FLOCKBAND manufactured by Rolf Meyer GmbH and available in the U.S. through the supplier International Knife and Saw, Inc. The material may be, for example, 2 to 3 mm in height with a width of 16 mm, and, before placement on the cylinder, has a substrate with adhesive tape and a removable backing. The hook portion (as opposed to the loop portion) of VELCRO tape is also a preferred sound-damping material.
The cylinder outer surface preferably includes a first section at a free end of the cylinder having a first outer diameter, the free end being opposite an end cantileverable in a gear-side frame. The first outer diameter preferably is smaller than a second section of the outer surface having a second diameter, the second section contacting an inner surface of the printing sleeve. This dual diameter arrangement of the cylinder advantageously permits easier placement of the sleeve over the cylinder, since the first reduced diameter section can act as a guide for the sleeve. The air holes may be located at a third section of the outer surface.
An alternate embodiment of the present invention includes a printing press comprising a cylinder having an outer surface, a plurality of air holes for providing air to the outer surface, and a free end, the outer surface having a threaded or roughened section at the free end, and an axially-removable printing sleeve for fitting over the outer surface. The roughened or threaded section is for reducing noise emanating from the printing press.
The present invention also provides a method for reducing noise from a printing press comprising the steps of:
providing air through air holes in a cylinder having a free end to aid in placement or removal of an axially-removable printing sleeve; and
providing a sound-damping surface to an outer surface of the cylinder at the free end.
A free end as defined herein is an end which may be free during a cantilevering operation. The free end may or may not be supported during a normal printing operation.